First of all, we were carried by our parents as babies, then crawled and finally started walking upright as we grew older.
This is significant because as babies we didn't know what's right or wrong, we were just ignorant, unable to take the right step. Then we grew a little bigger and our light started shining brighter helping us to learn to walk, and eventually we started walking upright. If light does not shine brighter at the part of the brain that aid in upright movement, human babies will not be able to walk upright.
Ofcourse, this is an inbuilt information or knowledge that automatically makes a child to start walking, without much effort put into learning to walk.
What this means in essence is that the brighter our light the more upright we become.